For mappings created in the Business Integration Converter (BIC) at times you need local or global procedures following the DRY principles in coding (Don't repeat yourself)
Maybe you need to enhance the BIC script by adding some inline Java code like shown in eg the unescapeHTML procedure found on these pages
It can be parameters in procedure signature or local variables, in the unescapeHTML procedure we can find this code
// Procedure parameter used in java code
String source = _StrVar_PSOURCE.getString();
You can find a lot of examples of this style of Java code in your build folders, in <source>\<project>\build\test\com\seeburger\jucon\mapping you can examine the Java files from your recent build
An example
// Java code example assigning an IDOC numer to a numeric variable
_NumVar_IDOC_NUMBER.setNum(stdin.getField("THIS:DOCNUM"));
Another small example which uses Java variables described is the getUUID method
You can find some examples on this site: Methods using inline Java